When optoelectronic devices such as an optical fiber and an optical emitter or receiver are to be connected to each other, the devices must be precisely aligned in order for the overall assembly to operate properly. For example, the optical axis of an emitter, such as a semiconductor laser, must be precisely aligned with that of the optical fiber, so that a laser beam emitted from the semiconductor laser enters the optical fiber properly.
Two methods of aligning optical devices are well known in the art. In “active alignment,” one optical device (typically the emitter) is turned on during the alignment process. The light beam emanating from the emitter passes through the fiber and is detected by a photodetector at the other end of the fiber. Relative movement between the emitter and the optical fiber is imparted until the photodetector detects a high or maximum light intensity, which indicates a desirable alignment. This trial-and-error method of active alignment is time-consuming and results in high fabrication costs.
In “passive alignment,” specific locations for each device on a substrate are set by micromachining while manufacturing the devices, and the devices to be optically connected are affixed thereto. Passive alignment can also be expensive because a manufacturer must tightly control the micromachining process so that each device is affixed in its exact location. A further problem with both active and passive alignment techniques is that once a desired alignment or a specific alignment location is determined, the two optical devices become permanently connected to one another.
As the data rates of computing backplanes (and consumer products such as video and mobile devices connecting to the backplanes) continue to increase, optical interconnections are expected to be preferred over copper lines. Therefore, there is a need for a low-cost, flexible optical interconnection package.